Zhao Xiaoxia He Junfang Wang Hongying Yang Senlin Li Yuanyuan Zhang Xiangwu

The fundamental harmonic of a pulsed Nd: YAG laser (1064 nm) was used for the ablation of copper and brass samples in air at atmospheric pressure and the laser-induced plasma characteristics were examined comparatively. The electron densities Ne of 3.6��1017 cm-3 in copper plasma and 3.3��1017 cm-3 in brass plasma were inferred from the Stark broadened profile of Cu I 324.75 nm averaged with 15 single spectra. In order to minimize relative errors in calculation of the electron temperature Te, an improved iterative Boltzmann plot method was used. Experimental results showed that the electron temperature in copper plasma was 6316 K larger than the value (6051 K) in brass plasma because the ionization potential of Zn(9.39 eV) is higher than that of Cu (7.72 eV). The plasma was verified to be in local thermodynamic equilibrium (LTE) and optical thin state based on the experimental results.